RISK FOR NEUROPATHOLOGICALLY CONFIRMED ALZHEIMERS-DISEASE AND RESIDUAL ALUMINUM IN MUNICIPAL DRINKING-WATER EMPLOYING WEIGHTED RESIDENTIAL HISTORIES

We investigated a possible relation between aluminum concentration ([A l]) in public drinking water and Alzheimer's disease (AD), with AD cas es and controls defined on the basis of strict neuropathologic criteri a, Using the case/control odds ratio as an estimate of relative risk a nd [Al] greater than or equal to 100 mu g/L as the cutoff point, eleva ted risks for histopathologically verified AD were associated with hig her [Al]. Comparing all AD cases with all non-AD controls, and using t he [Al] of public drinking water at last residence before death as the measure of exposure, the estimated relative risk associated with [Al] greater than or equal to 100 mu g/L was 1.7 (95% CI: 1.2-2.5). Estima ting aluminum exposure from a 10-year weighted residential history res ulted in estimates of relative risk of 2.5 or greater. The public heal th implications of the observed relationship between [Al] in drinking water and AD prevalence in the population depend in large measure on p opulation exposure characteristics. In Ontario, it is estimated that 1 9% of the population was exposed to residual [Al] greater than or equa l to 100 mu g/L. Based on the estimated relative risk and the assumpti on of causality, this translates to an etiologic fraction of 0.23. Alt hough the potential contributions of confounding and mitigating factor s are not defined in this report, the merit of limiting residual alumi num in drinking water supplies deserves serious attention.